Molecular Structure of the Fullerenes

Atomic Bonding. In order to account for the bonding of the carbon atoms of a fullerene molecule, the hybridization must be a modification of the sp hybridization of diamond and sp hybridization of graphite (see Ch. 2, Secs. 3.0 and 4.0). It is such that the sigma (o) orbitals no longer contain all of the s-orbital character and the pi (n) orbitals are no longer of the purely p-orbited character, as they are in graphite. 

The bond lengths of the fiillerenes are reported as 0.145 +/-0.0015 nm for the bonds between five- and six-membered rings, and 0.140 + - 0.0015 nm for the bond between the six-membered rings. ) 

Rgure 15.3. Hybridization of fulierene molecules as a function of pyramidization angle (0on - 90°). eon is the common angle of the three a bonds.l  

The Fuiierene Famiiy. Many fuiierene structures are theoretically possible, some with hundreds of atoms. Five have bean unambiguously identified and structurally characterized so far the Cao, C70, C g, and Cs4.r  

As the number of carbon atoms increases, the s-character in the n-orbital becomes less euid less pronounced to become zero in the case of the ideal graphite crystal, when the pyramidization angle is zero and the number of atoms is infinite. 

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